1 /* Copyright (C) 2003-2022 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18 #include <setjmp.h>
19 #include <stdio.h>
20 #include <stdlib.h>
21 #include <string.h>
22 #include <unistd.h>
23 #include "pthreadP.h"
24 #include <libc-diag.h>
25 #include <jmpbuf-unwind.h>
26 #include <shlib-compat.h>
27
28 #if _STACK_GROWS_DOWN
29 # define FRAME_LEFT(frame, other, adj) \
30 ((uintptr_t) frame - adj >= (uintptr_t) other - adj)
31 #elif _STACK_GROWS_UP
32 # define FRAME_LEFT(frame, other, adj) \
33 ((uintptr_t) frame - adj <= (uintptr_t) other - adj)
34 #else
35 # error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
36 #endif
37
38 static _Unwind_Reason_Code
unwind_stop(int version,_Unwind_Action actions,_Unwind_Exception_Class exc_class,struct _Unwind_Exception * exc_obj,struct _Unwind_Context * context,void * stop_parameter)39 unwind_stop (int version, _Unwind_Action actions,
40 _Unwind_Exception_Class exc_class,
41 struct _Unwind_Exception *exc_obj,
42 struct _Unwind_Context *context, void *stop_parameter)
43 {
44 struct pthread_unwind_buf *buf = stop_parameter;
45 struct pthread *self = THREAD_SELF;
46 struct _pthread_cleanup_buffer *curp = THREAD_GETMEM (self, cleanup);
47 int do_longjump = 0;
48
49 /* Adjust all pointers used in comparisons, so that top of thread's
50 stack is at the top of address space. Without that, things break
51 if stack is allocated above the main stack. */
52 uintptr_t adj = (uintptr_t) self->stackblock + self->stackblock_size;
53
54 /* Do longjmp if we're at "end of stack", aka "end of unwind data".
55 We assume there are only C frame without unwind data in between
56 here and the jmp_buf target. Otherwise simply note that the CFA
57 of a function is NOT within it's stack frame; it's the SP of the
58 previous frame. */
59 if ((actions & _UA_END_OF_STACK)
60 || ! _JMPBUF_CFA_UNWINDS_ADJ (buf->cancel_jmp_buf[0].jmp_buf, context,
61 adj))
62 do_longjump = 1;
63
64 if (__glibc_unlikely (curp != NULL))
65 {
66 /* Handle the compatibility stuff. Execute all handlers
67 registered with the old method which would be unwound by this
68 step. */
69 struct _pthread_cleanup_buffer *oldp = buf->priv.data.cleanup;
70 void *cfa = (void *) (_Unwind_Ptr) _Unwind_GetCFA (context);
71
72 if (curp != oldp && (do_longjump || FRAME_LEFT (cfa, curp, adj)))
73 {
74 do
75 {
76 /* Pointer to the next element. */
77 struct _pthread_cleanup_buffer *nextp = curp->__prev;
78
79 /* Call the handler. */
80 curp->__routine (curp->__arg);
81
82 /* To the next. */
83 curp = nextp;
84 }
85 while (curp != oldp
86 && (do_longjump || FRAME_LEFT (cfa, curp, adj)));
87
88 /* Mark the current element as handled. */
89 THREAD_SETMEM (self, cleanup, curp);
90 }
91 }
92
93 DIAG_PUSH_NEEDS_COMMENT;
94 #if __GNUC_PREREQ (7, 0)
95 /* This call results in a -Wstringop-overflow warning because struct
96 pthread_unwind_buf is smaller than jmp_buf. setjmp and longjmp
97 do not use anything beyond the common prefix (they never access
98 the saved signal mask), so that is a false positive. */
99 DIAG_IGNORE_NEEDS_COMMENT (11, "-Wstringop-overflow=");
100 #endif
101 if (do_longjump)
102 __libc_unwind_longjmp ((struct __jmp_buf_tag *) buf->cancel_jmp_buf, 1);
103 DIAG_POP_NEEDS_COMMENT;
104
105 return _URC_NO_REASON;
106 }
107
108
109 static void
unwind_cleanup(_Unwind_Reason_Code reason,struct _Unwind_Exception * exc)110 unwind_cleanup (_Unwind_Reason_Code reason, struct _Unwind_Exception *exc)
111 {
112 /* When we get here a C++ catch block didn't rethrow the object. We
113 cannot handle this case and therefore abort. */
114 __libc_fatal ("FATAL: exception not rethrown\n");
115 }
116
117
118 void
__cleanup_fct_attribute(noreturn)119 __cleanup_fct_attribute __attribute ((noreturn))
120 __pthread_unwind (__pthread_unwind_buf_t *buf)
121 {
122 struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
123 struct pthread *self = THREAD_SELF;
124
125 /* This is not a catchable exception, so don't provide any details about
126 the exception type. We do need to initialize the field though. */
127 THREAD_SETMEM (self, exc.exception_class, 0);
128 THREAD_SETMEM (self, exc.exception_cleanup, &unwind_cleanup);
129
130 _Unwind_ForcedUnwind (&self->exc, unwind_stop, ibuf);
131 /* NOTREACHED */
132
133 /* We better do not get here. */
134 abort ();
135 }
libc_hidden_def(__pthread_unwind)136 libc_hidden_def (__pthread_unwind)
137
138 void
139 __cleanup_fct_attribute __attribute ((noreturn))
140 ___pthread_unwind_next (__pthread_unwind_buf_t *buf)
141 {
142 struct pthread_unwind_buf *ibuf = (struct pthread_unwind_buf *) buf;
143
144 __pthread_unwind ((__pthread_unwind_buf_t *) ibuf->priv.data.prev);
145 }
146 versioned_symbol (libc, ___pthread_unwind_next, __pthread_unwind_next,
147 GLIBC_2_34);
148 #if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_3_3, GLIBC_2_34)
149 compat_symbol (libpthread, ___pthread_unwind_next, __pthread_unwind_next,
150 GLIBC_2_3_3);
151 #endif
152